Optical communications may be carried out over an optical fiber using optical signals processed with orthogonal functions such as Hermite-Gaussian functions, Laguerre-Gaussian functions and Ince-Gaussian functions as described herein in order to improve system bandwidth. Laguerre-Gaussian (LG), Hermite-Gaussian (HG), and Ince-Gaussian (IG) signals have three important properties and advantages. The advantages include the ability to form two complete families of exact and orthogonal solutions of the paraxial wave equations. Another advantage is that the HG, LG and IG signals are transverse eigenmodes of stable resonators. Finally, the HG, LG and IG signals do not change shape on propagation and provide stable modes of propagation for signals. However, when using LG, HG and IG signals for transmissions of various types on a particular mode there is often crosstalk between the mode being used and other adjacent modes on the transmission link. The crosstalk can have effects on the communications over the transmission link so some manner for tracking and illustrating the mode crosstalk effects over the transmission link would prove useful to system designers.